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include vmm.inc
 
VMMcall _LinMapIntoV86, <HLinPgNum, VM, VMLinPgNum, nPages, flags>
 
or      eax, eax            ; zero if error
jz      not_mapped
mov     [V86Address], eax   ; V86 address for mapped pages
 
The _LinMapIntoV86 service maps one or more pages into the V86 address space
of the specified virtual machine. This service is similar to the
_MapIntoV86 service but uses linear page numbers instead of memory handles.
Virtual devices that have access to memory handles should use the
MapIntoV86 instead of this service.
 
Parameter   Description
────────────────────────────────────────────────────────────────────────────
 
HLinPgNum   Specifies the linear page number of the first page to map. A
            linear page number is a ring-0 linear address shifted right by
            12 bits.
 
VM          Specifies a handle identifying the virtual machine for which
            memory is mapped.
 
VMLinPgNum  Specifies the linear page number of an address in the V86
            address space. The service maps the specified pages to this
            address if the HLinPgNum parameter does not already specify a
            valid V86 address. This parameter must be a page number in the
            range 10h through 10Fh.
 
nPages      Specifies the number of pages to map.
 
flags       Specifies the operation flags. This parameter must be set to
            zero.
 
Return Value
 
If the EAX register contains a nonzero value, the EDX register contains the
V86 address to which the specified pages are mapped. Otherwise, EAX contains
zero to indicate an error such as an invalid address range, an invalid
virtual machine handle, an illegal map range, a size discrepancy, or
insufficient memory locking. The EDX register contents are valid only if the
EAX register contains a nonzero value.
 
Comments
 
A virtual device typically uses this service to map buffers having
protected-mode addresses into the V86 address space. This gives software
running in the virtual machine a means of passing data to and receiving data
from the virtual device.
 
If HLinPgNum is a V86 page number (that is less than or equal to 100h), this
service returns HLinPgNum immediately and does nothing else. Otherwise, the
service returns VMLinPgNum.
 
If the specified linear pages belong to a free physical region, this service
calls the _PhysIntoV86 service to carry out the request.
 
If the specified linear pages belong to the high addressing region for a
virtual machine, this service maps the memory from that virtual machine into
the virtual machine specified by the VM parameter. The V86MMGR device uses
this capability to map a region of V86 address space which is currently
local to one VM into a global region that is addressable by all virtual
machines. Virtual devices must not use this capability directly; they should
always use the V86MMGR services to map local memory into global memory.
 
Although a virtual device can map the same page into multiple addresses in
the V86 address space, this is not recommended.
 
For each mapped page, this service sets the P_USER, P_PRES, and P_WRITE
bits, but clears the P_DIRTY and P_ACC bits. The service sets the page type
to be identical to the page type for the pages at the specified
protected-mode linear address.
 
If the virtual pageswap device uses MS-DOS or BIOS functions to write to the
device, this service automatically locks all mapped pages and unlocks any
previously mapped pages.
 
If a virtual device no longer needs the mapped region, it should map the
system nul page into the V86 address space using the _MapIntoV86 service. A
virtual device can retrieve the handle for the system nul page using the
_GetNulPageHandle service.
 
This service accepts V86 page numbers between 10h and the page number
returned by the _GetFirstV86Page service. This supports virtual devices that
use the _Allocate_Global_V86_Data_Area service. Mapping a region which spans
across the first V86 page is not allowed. Mapping pages in this region to
other addresses can easily crash the system, and should be avoided.
 
Uses
 
EAX, EDX
 
See Also
 
_Allocate_Global_V86_Data_Area, _GetFirstV86Page, _GetNulPageHandle,
_MapIntoV86, _PageLock, _PhysIntoV86
 
 
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